The nature of superluminal photon propagation in the gravitational field describing radiation from a time-dependent, isolated source (the Bondi-Sachs metric) is considered in an effective theory which includes interactions which violate the strong equivalence principle. Such interactions are, for example, generated by vacuum polarisation in conventional QED in curved spacetime. The relation of ...

We present an $LC$ circuit model that supports a tilted ``Dirac cone'' in its spectrum. The tilt of the Dirac cone is specified by parameters consisting mutual inductance between neighboring sites and capacitance ${C}_{0}$ at every lattice site. These can be completely measured impedance spectroscopy. Given described background spacetime metric, spectroscopy perfectly provide (local) informatio...

In the present paper a global conformal invariant Y of a closed initial data set is constructed. A spacelike hypersurface in a Lorentzian spacetime naturally inherits from the spacetime metric a diierentiation D e , the so-called real Sen connection, which turns out to be determined completely by the initial data h ab and ab induced on , and coincides, in the case of vanishing second fundamenta...

Citation Hohm, Olaf, and Barton Zwiebach. "Double metric, generalized metric, and-deformed double field theory. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. We ...

We use the recent discovered x−ψ duality to parameterize spacetime in terms of wave functions and quantum prepotentials. The components of metric, connection, curvature, Ricci tensor and scalar curvature as well as Einstein equations in this parameterization are

A simple model of spacetime foam, made by N wormholes in a semiclassical approximation, is taken under examination. We show that the qualitative behaviour of the fluctuation of the metric conjectured by Wheeler is here reproduced.